Toshiki Sasaki

49.4: High-definition Top-emitting AMOLED Display with Highly Reliable Oxide Semiconductor Field Effect Transistors

We have developed a highly efficient top-emitting white OLED by employing a stable reflective anode structure and a p-doped buffer layer. Furthermore, combining the white OLED with color filters, we succeeded in fabricating a prototype of a high-definition AMOLED display having highly reliable OS-FETs as the backplane.

P‐148: High‐Efficient Green OLED over 150 Im/W with New P‐doped Layer Exhibiting No Optical Loss Derived from Charge Transfer Complex

In order to maximize the power efficiency of OLEDs, a novel p-doped layer, which exhibits almost no voltage and optical losses, has been developed. By using this p-doped layer, we succeeded in fabricating a white tandem OLED over 30 lm/W with a high color temperature of 5,400 K and a green OLED of a top emission type over 150 lm/W.

Effect of halogenated impurities on lifetime of organic light emitting diode

We investigated a correlation between lifetime and the halogen element concentration in an organic light-emitting diode (OLED) and conducted experiments and simulations to discuss degradation mechanisms due to the halogen. OELD is generally formed of high-purity materials. Since the synthesis of high-purity materials takes time and cost, quantitative understanding of the kind, amount, and influence of impurities in OLED devices is expected. The results of combustion ion chromatography show that, if the chlorine concentration in the host material is more than several parts per million, the lifetime of the device is drastically reduced. The chlorine element, which is derived from the chlorinated by-product of the host material, is found to be transferred from the chloride to other materials (e.g., an emissive dopant) according to the results of LC-MS analysis. In addition, the electron transport layer including such impurities is also found to adversely affect the lifetime. The results of TOF-SIMS analysis suggest that the dissociated chlorine element diffuse to the light-emitting layer side when the device is driven. The results of simulations (Gaussian 09) and electrochemical analyses (cyclic voltammetry and electrolysis) reveal that the halogen element is easy to dissociate from halide by excitation or reduction. The halogen element can repeat reactions with the peripheral materials by excitation or reduction and cause damages, e.g., generate radicals or further reaction products due to the radicals. The results of simulation suggest that, such compounds have low energy level and become quenchers.